(1) Field of the Invention
The invention relates to a water refilling control mechanism for a water tank, and more particularly to which comprises a main float and an auxiliary float for temporarily suppressing the main float during water feeding, and suddenly stopping the water feeding by releasing the suppressed main float after reaching a substantial water lever.
(2) Description of the Prior Art
It is well known that a water tank, especially one used in a toilet, needs plenty of water daily to perform its function. The water refilling process of a water tank is controlled by a set of water feeding control devices for automatically regulating the water feeding into the water tank. Conventionally, most water tanks in the market utilize a water feeding control device as shown in FIG. 1. The water feeding control device comprises an inlet pipe 10 installed upright from the bottom of the water tank, a float ball 11, a supporting bar 12, an adjusting head 13, and a water valve 14. The elevation of the float ball 11 in the water tank is determined by the water level therein. The movement of the float ball 11 is transmitted to the adjusting head 13 via the supporting bar 12 connected with the float ball 11 at one end, and connected pivotally close to the adjusting head. By the levering theory, the adjusting head 13 will be pressed down or be released by the other end of the supporting bar 12 for automatically controlling the water valve to stop the water refilling or process the water feeding, respectively, while the float ball 11 is moving up or down accordingly to the water level in the water tank. In such a design of a known the water feeding control device, the magnitude of the pressure in the water valve 14 for stopping the water feeding is determined by the buoyant force of the float ball 11 and the length of the supporting bar 12. Therefore, to provide a sufficient stopping pressure for the water valve 14, a large-volume float ball 11 and a lengthy supporting bar 12 are usually seen for the water feeding control device in the art.
In the water feeding control device shown in FIG. 1, the supporting bar 12 rotates pivotally with the elevating of the float ball 11, and the adjusting head 13 is then pressed down by one end of the supporting bar 12, while the water level reaches a substantial level, in order to directly stop the water feeding by closing the water valve 14. The efficiency of such a water feeding control algorithm is highly dependent upon the length of the supporting bar 12 and the volume of the float ball 11. Thus, a large float ball 11 and a long supporting bar 12 are necessary for obtaining better performance of the water feeding control device.
To overcome the aforesaid disadvantage in the known water feeding control device and to minimize the volume of a water tank, a membrane-type water feeding control device has been developed. As shown in FIG. 2, the water valve 14 utilized in a membrane-type water feeding control device comprises a stopper 140 directly connected with the adjusting head 13. The stopper 140 is further shielded by a first spring 141 and is located on top of an air hole 143 of a top cover 142. Beneath the air hole 143 is a membrane 145 supported by a second spring 144. The membrane 145 further includes a through needle 146 located thereof in the middle. The control of this type of water feeding control device begins with the supporting bar 12 pressing down the adjusting head 13 and then the stopper 140, the stopper 140 blocking the air hole 143, the air chamber 147 between the stopper 140 and the membrane 145 generating a pressure to press down the membrane 145 at the central area thereof so as to block the water inlet 148 thereunder, and finally blocking the water feeding by blocking the water outlet 149. The membrane-type water feeding control device utilizes the pressure difference to control the water feeding. Therefore, the supporting bar 12 and the float ball 11 are deemed as auxiliary parts, so that the length of the supporting bar 12 and the volume of the float ball 11 less important. As a matter of fact, the volume of water tank utilizing a membrane-type water feeding control device can be reduced by using a shorter supporting bar 12 and a smaller float ball 11.
Referring now to FIG. 3, the supporting bar 12' and the float ball 11' can be modified accordingly. In this embodiment shown in FIG. 3, the float ball 11' is installed as a sliding block along the inlet pipe 10, and the supporting bar 12' is indirectly connected with the float ball 11' by a vertical extension bar 15. The float ball 11' is to float up according to rising of the water level, and the supporting bar 12' is pushed by the extension bar 15 to stop the water feeding.
Compared with the traditional water tank, the water tank utilizing a membrane-type water feeding control device can have a smaller volume and is conveniently to be manufactured as one piece. Although the introduction of the membrane-type water feeding control device did solve the volume problem of a conventional tank, yet another shortcoming of both types of aforesaid water tanks remained.
The problem comes from the float ball. In a conventional water tank, the only force source is the buoyant force of the float ball. So, as the water level in the water tank is rising, the float ball will float accordingly. As long as the water level reaches a substantial height, the water feeding will be stopped by the force exerted by the float ball. Nevertheless, a water feeding control device in the art only has 1/3 of total volume of the float ball under the water level. That is, only about 30% of total volume of the float ball contributes to the buoyant force in generating force for controlling the water valve to close the water feeding. Obviously, such a low ratio is unsatisfactory. Also, the force generated for control is usually insufficient. Therefore, as we have observed in the conventional water tank, the water level keeps rising gradually even after the float ball seems to reach the highest point and the inlet pipe seems to stop feeding water. After investigation, it is found that the major cause responsible to such phenomena is the low utilization ratio of the float ball volume toward the buoyant force generation; so that insufficient pressure is generated for blocking the water valve. As long as the water valve is not completely closed, the water will keep flowing into the water tank gradually. Such a flowing caused by insufficient pressure for closing the water valve not only shows that the conventional water tank needs to be further modified, but also.